I am about to add a new vinyl window to an existing exterior garage wall. The inside of the garage wall is now just open studs, but I will be adding insulation to the wall and then sheetrock.
The outside of the wall is aluminum siding on top of some type of 1/2 inch siding (I don't know what it is called) that is nailed to the studs. Cutting the opening for the window and framing it out with a header etc. will not be a problem -- I know how to do that.
My question is about what to do on the outside. If I buy a new window, it will have a flap/flange(?) around the outside that is for nailing the new window to the studs. But, if I cut back the aluminum siding to allow for the flaps to be nailed to the studs, how do I finish off the space between the edge of the aluminum and the window itself?
Is there some other trick for doing this such as to cut off the flaps and nail the window in place through the sides so the aluminum will meet the edge of the window?